Rôle de la régulation stomatique et de la capacité de détoxication foliaire dans l'estimation d'un seuil de risque à l'ozone pour la végétation

Abstract : Tropospheric ozone is a major air pollutant that acts as a phytotoxin. It enters the leaf through the stomata before being dissolved in the apoplast by generating reactive oxygen species (ROS) causing oxidative stress. Two defenses exist to restrict the effects of ozone: (i) the stomata which can limit ozone uptake by regulating stomatal conductance and (ii) the detoxification processes of ROS generated by ozone.We studied the effects of ozone (120 ppb) on these two mechanisms of defense in three euramerican poplar genotypes (Populus deltoides x Populus nigra) under controlled conditions in phytotronic chambers. A direct effect of ozone on photosynthesis and stomatal movements in response to changes in environmental factors (by slowing the stomatal opening and closure) has been highlighted. Models of stomatal conductance, on which indicators of critical level of ozone for vegetation are based, must take them into account. In addition, these studies have highlighted the role of constitutive concentrations of antioxidants in tolerance to ozone as well as the complexity of these detoxification mechanisms. The notion of effective ozone flux must consider these two aspects to better characterize the intra-and inter-specific differences in sensitivity to ozone
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Jennifer Dumont. Rôle de la régulation stomatique et de la capacité de détoxication foliaire dans l'estimation d'un seuil de risque à l'ozone pour la végétation. Biologie végétale. Université de Lorraine, 2013. Français. ⟨NNT : 2013LORR0022⟩. ⟨tel-01749383⟩

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